Rotary dehydrator having anti-discharge structure for moisture-laden materials

ABSTRACT

A rotary dehydrator advances moisture-laden materials from an inlet of a rotating drum toward an outlet thereof while simultaneously lifting and tumbling the materials into and through a heated airstream flowing axially through the drum. An inclined baffle overlying the outlet obstructs access to the latter by the tumbling materials and by those materials entrained within the airstream so that only the materials which have been dehydrated to the desired extent can overcome the obstruction and be carried from the dehydrator by the discharging airstream. The baffle is extensible and may be adjusted angularly with respect to the outlet whereby to provide selectivity in controlling the specific gravity of the materials being discharged.

[ Nov. 26, 1974 1 ROTARY DEHYDRATOR HAVING ANTI-DISCHARGE STRUCTURE FOR MOISTURE-LADEN MATERIALS [75] Inventor: Wallace L. McGehee, Kansas City,

[73] Assignee: American Pollution Prevention Co.,

Inc., Minneapolis, Minn.

22 Filed: Oct. 29, 1973 [21] Appl. No.: 410,495

2,720,340 10/1955 Gustafson 222/556 3,088,711 5/1963 Phillips 3,245,154 4/1966 Bojner et a1. 34/135 Primary Examinerl(enneth W. Sprague Assistant Examiner-Larry l. Schwartz Attorney, Agent, or FirmSchmidt, Johnson, Hovey & Williams [5 7 ABSTRACT A rotary dehydrator advances moisture-laden materi' als from an inlet of a rotating drum toward an outlet thereof while simultaneously lifting and tumbling the materials into and through a heated airstream flowing axially through the drum. An inclined baffle overlying the outlet obstructs access to the latter by the tumbling materials and by those materials entrained within the airstream so that only the materials which have been dehydrated to the desired extent can overcome the obstruction and be carried from the dehydrator by the discharging airstream. The baffle is extensible and may be adjusted angularly with respect to the outlet whereby to provide selectivity in controlling the specific gravity of the materials being, discharged.

2 Claims, 4 Drawing lFigures ROTARY DEHYDRATOR HAVING ANTI-DISCHARGE STRUCTURE FOR MOISTURE-LADEN MATERIALS drum while repeatedly introducing and reintroducing the same to a heated airstream moving through the drum. It is important that a degree of control be provided over the materials at the discharge end of the dehydrating process so that those materials which are not yet fully dehydrated are retained for further processing, while those which have their moisture removed to the desired level are discharged. Certain materials may dry more or less rapidly than others and may also be more or less easily entrained within a stream of heated air flowing through the dehydrator than others, thus redisposed escape passage for heavier moisture-laden materials. By varying the position of the end of the tube with respect to the lateral escape passage, the specific gravity and thus the moisture content of the materials leaving through the discharge tube could be closely controlled. By positioning the end of the tube closer to the escape passage, the heavier, moisture-laden materials could be carried by the airstream into the tube, but by disposing the tube a greater distance from the escape passage, the moisture-laden materials might be too heavy to be carried such a substantial distance to the tube, thereby gravitating to the escape passage instead of being carried out through the tube.

The present invention provides an alternative to the.

discharge control structure disclosed in my aforementioned Patent and has, as its primary object to provide a non-complex, virtually maintenance-free and highly reliable means for controlling the specific gravity and thus the moisture content of materials being discharged from the dehydrator.

Another important object of this invention is to pro vide selectivity in the control of the materials being discharged from the dehydrator so that different material characteristics and variations in the desired moisture content of the materials being discharged can be accommodated.

Pursuant to the foregoing objects, a further important aim of this invention is to provide inclined baffle structure overlying the outlet of a rotary dehydrator wherein the baffle structure can be extended and retracted to the extent necessary to properly position the .lower end thereof with respect to the outlet in accordance with the characteristics of the materials being processed and the desired end moisture content.

An additional important object of this invention is to provide baffle structure as aforesaid which can be adjusted angularly with respect to the outlet to provide an additional means of controlling selectivity.

In the drawing:

FIG. 1 is an elevational view of a dehydrator constructed in accordance with the teachings of the present invention, the upper half of the rotary drum thereof being broken away to reveal details of construction;

FIG. 2 is a vertical cross-sectional view through the dehydrator taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged, fragmentary, vertical crosssectional view through the discharge end of the dhydrator showing details of the special baffle structure; and

FIG. 4 is a fragmentary, cross-sectional view of the baffle structure taken along line 44 of FIG. 3.

The dehydrator has an elongated, tubular drum 10 that is supported at the bottom thereof by a pair of drive rolls 12 for rotating the same in a clockwise direction viewing FIG. 2. The drum 10 is closed at its opposite ends by a pair of stationary end walls 14 and 16 supported by frame apparatus 18, the end wall 14 having an inlet conduit 20 coaxially disposed with drum 10 for admitting heated air and moisture-laden materials into the latter, and the opposite end wall 16 having an outlet conduit 22. The outlet conduit 22 registers with an outlet opening 24 in end wall 16 (FIG. 3), and it is to be understood that although not shown, a similar opening is provided in end wall 14 for inlet conduit 20. It is to be further understood that the inlet conduit 20 is coupled with a source of heated air, while the outlet conduit 22 is coupled with means for drawing such heated air through drum 10 axially of the latter in a steady stream.

A series of longitudinally extending, circumferentially spaced, L-shaped lifters 26 are secured to the interior wall of drum 10 for repeatedly lifting and tumbling the materials that are introduced into drum 10 through conduit 20. Thus, the lifters 26 repeatedly introduce the materials to the heated airstream that is flowing through drum 10 in order to continuously expose the materials to the effects of such airstream.

The discharge end of the drum 10 has structure broadly denoted by the numeral 28 for controlling the moisture content of the materials leaving drum 10 through outlet opening 24 and conduit 22. Specifically, the structure 28 includes a sectionalized baffle 30 that overlies opening 24 in an inclined attitude to present an obstruction to the exiting airstream and to the materials that are tumbling within drum 10 adjacent opening 24.

The baffle 30 is rendered extensible by virtue of its sectionalized construction, there being an upper section 32 having an upper terminus 34 that defines the upper end of baffle 30 and which is secured to end wall 16 by a hinge 36, and a lower section 38 slidable within upper section 32 for shifting between the solid and dotted-line positions illustrated in FIG. 3. The lower section 38 has a terminus 40 that defines the lowermost end of baffle 30, the position of such lowermost end being varied with respect to opening 24 by retracting or extending lower section 38. As illustrated in FIG. 4, the upper section has intumed flanges 42 along the underside thereof that slidably support the lower section 38. Suitable means such as a cable 44 looped over a pulley 46 and connected to lower section 38 may be used to shift the latter between its variable positions.

Angular adjustment of baffle 30 is provided for by a pair of shiftable support members 48 disposed on opposite sides of baffle 30 and pivotally secured to the upper section 32 by pivots 50. Each of the members 48 extends through an aperture 52 (FIG. 2) in end wall l6 and has a series of teeth 54 which may be selectively engaged with the lower extremity of the aperture 52 to releasably lock the baffle 30 in its selected position. Adjustment of such position may be easily carried out by simply raising the outermost ends of the members 48 to disengage their teeth 54, and then shifting the members 48 longitudinally in the appropriate direction to swing baffle 30. Reengagement of the teeth 54 in their apertures 52 once again locks the baffle 30 against swinging.

As earlier set forth, while the drum is being rotated by the rolls 12, a strong current of heated air is drawn through drum 10 axially thereof by way of the conduits and 22. Moisture-laden materials are fed into drum 10 through inlet conduit 20, whereupon they are repeatedly lifted and tumbled by the lifters 26 to be continuously exposed to the heated airstream. The combined effects of the tumbling action and the airstream advance the materials progressively toward outlet opening 24 and outlet conduit 22 and, ideally, by the time the materials approach end wall 16 they are sufficiently dehydrated to be entrained within the airstream and carried out of drum 10 through conduit 22.

By virtue of the control structure 28, it is possible to closely regulate the moisture content of the materials that are carried out of drum 10 by the airstream. In this respect, the baffle 30, by virtue of its overlying relationship to the opening 24, functions as an obstruction to the otherwise unimpeded access to opening 24, thus momentarily diverting the airstream out of its otherwise truly axial path of travel. Such deviation of the airstream may be sufficient to cause those particles which are barely entrained in the airstream to lose their momentum and be deflected out of the airstream, gravitating into the bottom of drum 10 for re-tumbling and reintroduction into the airstream. This action results in further dehydrating of the blocked particles until such time as they can be once again entrained in the airstream and have sufficient energy to overcome the obstruction presented by baffle 30. Of course, those materials which are sufficiently dehydrated in the first instance to overcome the effects of baffle 30 will simply remain entrained within the airstream and leave drum 20 through conduit 22.

The presence of baffle 30 also prevents the escape from drum 10 of those materials which are tumbling adjacent end wall 16 but have not as yet been fully entrained within the airstream. In this respect, it will be appreciated that the suction force closely adjacent opening 24 can be greater than that at the center of drum 10, for example, and thus, while the moistureladen materials might be too heavy to become entrained in the airstream near the center of drum 10, they might undesirably be sucked out of drum 10 when they gravitate across opening 24 without the presence of baffle 30. Because of the inclined nature of baffle 30, when such still moist materials drop from near the top of drum 10 to pass across opening 24, they instead engage the top of baffle 30 and roll down the same toward lower terminus 40, at which point they are too far removed from opening 24 to be affected by the strong suction at that location.

By varying the extent of projection of lower section 38 from upper section 32, the moisture content of the materials being carried out of drum 10 by way of conduit 22 can be regulated. When, for example, the lower section 38 is extended to its dotted line position as illustrated in FIG. 3, the horizontal distance between the point at which the airstream is released from the obstruction presented by baffle 30, and the opening 24 is substantially greater than the distance between the same two points when the lower section 38 is in its solid line position of FIG. 3. Accordingly, the materials which are entrained within the airstream when the lower section 38 is so extended must overcome an effectively greater obstruction than before and must travel a greater distance after such obstruction than before, thereby permitting only those materials having lower moisture content to be carried from drum 10. By selectively positioning the lower section 38 between the two extreme locations illustrated in FIG. 3, intermediate moisture levels can be obtained as a function of the distance between lower terminus 40 and the opening 24.

In a similar manner, adjustment of the lower section 38 controls the departure of those materials which are too moist to be entrained within the airstream at a point remote from opening 24, but which drop past the latter during their tumbling action and might be accidentally sucked out of drum 10 at that point. By extending lower section 38 beyond the solid line position thereof in FIG. 3, the point at which the moist materials drop off baffle 30 and are exposed to the direct suction at opening 24 can be spaced further from the latter as necessary or desirable.

The adjustability of baffle 30 in an angular respect is also quite beneficial in that such adjustment, effected through the members 48, also causes horizontal displacement of the terminus 40 of section 38. Therefore, at a selected extension of section 38 as determined by cable 44, the terminus 40 may be shifted arcuately in the direction and to the extent desired to displace terminus 40 horizontally in accordance with the characteristics of the specific materials being dehydrated. Thus, by combining the angular adjustment of baffle 30 with the extensible adjustment thereof, a very precise and highly selective control over the moisture content of the materials leaving drum 10 can be effected.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

I. In a rotary dehydrator:

an elongated, tubular drum mounted for rotation about its longitudal axis;

a pair of stationary end walls for said drum,

one of said end walls having an inlet to the interior of said drum for introducing moisture-laden materials and a heated stream of air into the drum,

the opposite end wall having an outlet from the drum for discharging dehydrated materials entrained within said airstream from the drum;

'means within said drum for repeatedly lifting and tumbling the materials into and through said airstream as said drum is rotated and as the materials advance toward said opposite end wall; and

an inclined baffle overlying said outlet for obstructing access to the latter by the tumbling materials and those entrained within said airstream for preventing the discharge of those materials not sufficiently dehydrated to be carried out the outlet with said airstream,

said baffle having an upper and a lower end,

lower end toward and away from said opposite end wall, and wherein means is provided for supporting the baffle in any one of a number of angled positions along the path of swinging movement thereof. 

1. In a rotary dehydrator: an elongated, tubular drum mounted for rotation about its longitudal axis; a pair of stationary end walls for said drum, one of said end walls having an inlet to the interior of said drum for introducing moisture-laden materials and a heated stream of air into the drum, the opposite end wall having an outlet from the drum for discharging dehydrated materials entrained within said airstream from the drum; means within said drum for repeatedly lifting and tumbling the materials into and through said airstream as said drum is rotated and as the materials advance toward said opposite end wall; and an inclined baffle overlying said outlet for obstructing access to the latter by the tumbling materials and those entrained within said airstream for preventing the discharge of those materials not sufficiently dehydrated to be carried out the outlet with said airstream, said baffle having an upper and a lower end, said baffle being extensible for varying the position of said lower end with respect to said outlet.
 2. In a rotary dehydrator as claimed in claim 1 wherein said baffle is hinged at said upper end thereof to said opposite end wall for swinging movement of said lower end toward and away from said opposite end wall, and wherein means is provided for supporting the baffle in any one of a number of angled positions along the path of swinging movement thereof. 